The present invention is directed to an end cap for an actuator and more specifically to an end cap having a breather passage complementary to a breathing hole in the housing of an actuator such as an electric motor or an electromagnetic valve.
An end cap is often provided on an electric motor actuator for waterproofing the actuator which is used, for example, in a cruise control system for controlling a throttle valve opening. An example of a conventional end cap is disclosed in FIG. 8.
As shown in FIG. 8, an actuator 100 includes a motor housing 101 having a cover 102. An output shaft 103 projects from the actuator 100 and the actuator 100 is fixed to the vehicle body BD by means of bolts 1e, only one of which is shown in FIG. 8. The output shaft 103 is operatively connected with a drive unit (not shown) which is accommodated in the motor housing 101. A seam or joint 104 is formed between the motor housing 101 and a cover 102. An end cap 200 is fitted on the actuator 100 over the cover 102 to seal the joint 104. The motor housing 101 and the motor cover 102 define a space 105 therein in which the drive unit is adapted to be located. A breathing hole 106 is formed in the side surface of the motor housing 101 for establishing fluid communication between the internal space 105 and the atmosphere. A breather pipe 300 having a through passage 301 is fitted in the hole 106.
When the actuator 100 is actuated, a negative pressure is created in the space 105 due to the rotation of the drive unit. If any water drops are disposed on the actuator 100, especially on the pipe 300 in the vicinity of the passage 301, the water droplets will be sucked into the actuator 100 due to the negative pressure therein. This creates a serious problem since water can severely damage the actuator drive unit.